Store-and-forward devices, such as switches and routers, are used in packet networks, such as the Internet, for directing traffic at interconnection points. The store-and-forward devices include a plurality of line cards for receiving and transmitting data from/to external sources. The line cards are connected to one another via a backplane and a switching fabric. The backplane provides data paths between each line card and the switching fabric and the switching fabric provides configurable data paths between line cards. The backplane consists of a plurality of links (channels). Each channel is capable of transmitting data at a certain speed. If the line cards are transmitting data at speeds faster than the capabilities of the channels, the line cards can break the data up into sections and transmit the sections in parallel over several channels (strip the data). The number of channels required to support the line cards is based on the speed of the line cards and the capacity of the channels.
When a store-and-forward device has line cards operating at different speeds, the number of channels associated with each line card is based on the number of channels required for the line card operating at the highest speed. Accordingly, there will be channels associated with lower-speed line cards that are not used. Additionally, the switching fabric will have ports that are not used. This is an inefficient use of resources. The inefficiency grows as the difference in speed between line cards grows. As the capacity of switches and routers increases, the need for supporting ports with different speeds is becoming more common. Users need to be able to plug in legacy line cards into new systems, while populating a few slots with new line cards supporting ports with higher data rates. For example, an Internet router may have line cards with OC-48 and OC-192 ports today, and may need to support line cards with OC-768 ports in the future. In addition, higher-density line cards where the traffic from many external ports is aggregated into a single fabric port may require higher data-rate fabric ports.